TI-83+ Solana Hardware Wallet

This repository contains a proof-of-concept hardware wallet that runs on a TI-83 Plus graphing calculator. The calculator hosts the signing logic, communicates with a connected computer over the TI Link cable, and produces Solana-compatible signatures without exposing private keys.

The project blends calculator-side firmware written in C with vendored cryptography and TI connectivity libraries. Together they deliver an end-to-end pipeline: capturing user intent, deriving key material, framing Solana transactions, and returning signed payloads for broadcasting.

Repository Layout

• main.c: Entry point that boots the calculator app, wires up session state, and drives the polling loop.
• calc_session.c/.h: Abstractions for the TI Link stack, including session lifecycle, cable detection, and message polling.
• calc_string_store.c/.h: Lightweight helpers for storing and retrieving calculator string variables.
• wallet_crypto.c/.h: High-level wallet primitives such as key derivation and signature orchestration built on the vendored Ed25519 stack.
• examples.c: Reference snippets that exercise the link layer and signing flow for development and testing.
• solana/: Modules specific to Solana encoding and client operations.
• keypair/: Vendored Ed25519 implementation used for key generation, hashing, and signature creation.
• tilibs/: Vendored TI connectivity libraries providing cable drivers, calculator protocol helpers, and file format utilities.

Desktop UI (ui/)

A Rust/Dioxus desktop application that wraps the C library via FFI, providing a graphical interface for all wallet operations.

• cwallet-sys/: FFI bindings crate — manual declarations for all C functions (no bindgen).
• cwallet-ui/: Dioxus 0.6 desktop app with sidebar navigation, keypair management, and Solana operations.

Features:

• Connect/disconnect TI-83+ calculator
• Create and load keypairs across 10 slots (Str0–Str9)
• Check SOL balance, request devnet airdrops, send SOL transfers
• Adaptive light/dark theme following system appearance

Solana Modules (solana/)

• solana_client.c/.h: Handles message framing between the calculator and host, translating inbound requests into wallet actions and packaging outbound responses.
• solana_encoding.c/.h: Provides Solana-specific serialization, including base58-style layouts and transaction message encoding used before hashing and signing.

Vendored Cryptography (keypair/)

The keypair directory is imported wholesale to keep verification consistent with audited upstream code. The upstream implementation targeted a 64-byte private key layout; this fork carries minimal patches so the serialization and key derivation align with Solana expectations while leaving the core curve arithmetic untouched:

• ed25519.h: Public API exposing key generation, signing, and verification entry points.
• fe.*, ge.*, sc.*: Finite-field, group-element, and scalar arithmetic that back the curve operations.
• sha512.*: Hashing primitives sourced from the same upstream project, ensuring deterministic seed expansion.
• sign.c, verify.c, keypair.c: High-level routines that wrap the arithmetic layers to deliver Ed25519 keypair generation and signature workflows.
• Supplementary helpers (add_scalar.c, seed.c, key_exchange.c, precomp_data.h) provide advanced operations such as hierarchical key derivation and precomputed tables.

Vendored TI Connectivity Libraries (tilibs/)

The tilibs folder tracks the official TilEm project libraries with minimal local modification. Each subproject builds into static libraries consumed by this calculator application:

• libticables: Hardware cable backends for USB SilverLink and other TI link adapters, handling low-level transport details.
• libticalcs: Calculator protocol logic that sits on top of libticables, managing device discovery, command dispatch, and data framing.
• libticonv: Character set and encoding utilities used when exchanging strings or filenames with the calculator OS.
• libtifiles: Parsers and writers for TI calculator file formats, enabling structured transfer of variables or application data.

Because both keypair and tilibs are vendored, keep changes limited and document any deviations from upstream sources. The Solana-specific adjustments in keypair/ are tracked locally to avoid regressions.

Build and Run Workflow

All development tasks are orchestrated through the top-level Makefile:

• make configure: Runs CMake configuration, creates the build/ directory, and refreshes the compile_commands.json symlink for tooling.
• make build: Compiles the calculator application alongside all required vendored libraries.
• make run: Launches the compiled main executable, starting the interactive polling loop. Requires a TI-83 Plus connected via USB SilverLink or equivalent.
• make clean: Removes the build/ directory and clears generated binaries for a fresh rebuild.
• make menu: Enables vendor regression tests by configuring CMake with -DENABLE_VENDOR_TESTS=ON, builds the test harness, and executes test_ticalcs_2 against a SilverLink cable for protocol verification.

For deeper validation of the vendored TI libraries, review TI_TILibs_Cheatsheet.md and the test programs under tilibs/libticalcs/trunk/tests/.

Getting Started

CLI

1. Install a modern C toolchain with CMake support (C11 compatible compiler and make).
2. Connect a TI-83 Plus via a TI USB SilverLink cable or simulator that exposes the same protocol.
3. Run make configure followed by make build to compile the project.
4. Execute make run to start the calculator-host interaction loop.

Desktop UI

1. Install Rust and ensure pkg-config and glib-2.0 are available.
2. From the ui/ directory, run cargo run -p cwallet-ui.
3. The desktop window will open — connect your calculator using the top-right button, then select a keypair slot from the dropdown.